This dissertation evaluates equity and access in higher education through three distinct empirical studies: a regression discontinuity design, a meta-analysis, and an institutional-level regression analysis. First, the dissertation employs a Fuzzy Regression Discontinuity design to estimate the causal effects of Georgia State University’s Summer Success Academy (SSA) on conditionally admitted students. This study finds a statistically significant positive effect on student persistence, particularly for Pell Grant recipients. The analysis does not find a corresponding positive effect on cumulative GPA. Second, a meta-analysis synthesizes the existing evidence on summer bridge programs (SBPs) for at-risk students. This study finds a modest, statistically significant positive association with first-year persistence. This finding, however, must be interpreted with caution, given significant heterogeneity, a high risk of bias, and potential publication bias in the underlying literature. Third, an institutional-level OLS regression examines the association between institutional racial/ethnic diversity and social capital formation. This study finds that institutional context moderates diversity's baseline negative association with the formation of cross-class social ties, which becomes attenuated or positive in institutions with greater financial resources or a larger low-income, Pell-recipient student population. Collectively, this research contributes to the understanding of equity and access by demonstrating that support interventions show measurable impacts on persistence, while institutional context is critical in moderating the social outcomes of diversity.